1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus configured to form a plurality of scanning lines by scanning a light beam to and fro on an image carrying body, and a control method thereof.
2. Description of the Related Art
An image forming apparatus forms an electro-static latent image, then a visible image thereof, by way of a developer applied on an image carrying body, and transcribing the visible image on to a print medium to form an image. Specifically, the image forming apparatus includes a light scanning unit to form the electro-static latent image by scanning a light beam in a main scanning direction with respect to the image carrying body moving partially in a sub scanning direction (i.e., an output direction).
The light scanning unit includes a beam deflecting unit to deflect and project the light beam, whereby the beam deflecting unit may be operated by a polygonal mirror method to scan the light beam in a predetermined direction, or a resonance mirror method to scan the light beam to and fro in one direction and then an opposite direction.
In a typical image forming apparatus, the beam deflecting unit utilizing the resonance mirror method scans the light beam to and fro along the main scanning direction on the image carrying body, and at the same time, the image carrying body moves or rotates partially in the sub scanning direction (or the output direction) at an equal speed. Thus, a plurality of the scanning lines is arranged in parallel along the sub scanning direction on the image carrying body to form the electro static latent image. However, because the typical image forming apparatus has the beam deflecting unit scanning the light beam to and fro, while the image carrying body is moved or rotated, the scanning lines are zigzagged on the image carrying body. Thus, gaps between adjacent scanning lines provided along the main scanning direction are not regular. If the gaps between the scanning lines along the sub scanning direction are not regular as described above, the quality of a final image becomes poor when the final image is formed by transcribing the visible image of the image carrying body onto a print medium.